Fig. 1: Resistance to ERK/MAPK inhibition is supported by long-term epigenetic and transcriptional changes.

a FVB/n mice implanted orthotopically with 10³ 2.1.1^syn_Luc cells and treated with either vehicle (20% HpBCD) or SCH772984 (35 mg/kg), with luminescence reported as mean and standard deviation, N = 10 mice per group. Representative micrographs (b) and immunoblots (c) of orthotopic tumors treated with vehicle (20% HpBCD) for 48 h, SCH772984 (35 mg/kg) for 48 h, or SCH772984 (35 mg/kg) for four weeks. The immunoblots are performed with two biologic replicates, and the micrographs are representative of two biologic replicates. d Left, hierarchical clustering of RPPA protein expression changes in MIA PaCa-2 cells treated with SCH772984 (1 µM) relative to DMSO (1:1000), performed in triplicate, with individual proteins annotated by cellular function and clusters indicated by circled numbers. Right, restrictive cubic splines of relative growth rate (total doublings per day) of SCH772984-treated cells compared to DMSO-treated cells (top), as well as selected protein expression changes within MAPK and PI3K/AKT/mTOR signaling pathways (middle) and cell cycle/translation markers (bottom). e Venn diagram depicting total H3K27ac peaks gained or lost (FDR < 0.1) in MIA PaCa-2 cells treated with SCH772984 (1 µM) compared to DMSO (1:1,000) for either one week (early) or eight weeks (stable resistance), performed in duplicate. (f) Scatter plot comparing gene expression changes in MIA PaCa-2 cells treated with SCH772984 (1 µM) compared to DMSO (1:1000) for either one week (early) or eight weeks (stable resistance), performed in triplicate. Each dot represents a single gene, with colored dots representing statistically significant (p < 10⁻³) gene expression changes at the indicated time points, with statistical significance determined by Wald test using the Benjamini and Hochberg method to correct for multiple hypothesis testing. Error bars represent standard deviations.